(a) Technical Field of the Invention
The present invention is generally related to an automatic gain control method for radio-frequency (RF) signal, and more particular to a RF signal automatic grain control method capable of maintaining RF output signal within a specified dB range.
(b) Description of the Prior Art
Electronic devices are often operated under various control circuits to achieve desired performance. Feedback is a major mechanism utilized by numerous control circuits and therefore they are often named as feedback control circuits. The so-called automatic gain control (AGC) circuit is one such control circuit.
AGC circuit is commonly applied in radio-frequency (RF) reception devices. This is due to that RF signal suffers significant fluctuation resulted from factors like multiple paths and attenuation in the transmission process. The AGC circuit is used to maintain the stability of RF output signal's dB value.
For conventional AGC circuit, once channel loading to the RF input signal changes, a reference value fed back by the AGC circuit has to be manually adjusted to as to maintain the stability of RF output signal's dB value, which is cumbersome to operation personnel.